The present invention relates to a pinch valve used in a fluid transport pipeline in various industrial fields, such as chemical factories, semiconductor production, food processing, biotechnology or the like, and more particularly, to a pinch valve which is compact and mitigates the damage a tube body suffers during opening and the closing of the valve.
Hitherto, various pinch valves have been proposed, and an example is disclosed in Japanese Examined Utility Model Publication No. 45-3264. According to this publication, as shown in FIGS. 27 and 28, in two upper and lower pistons 41, 42 fitted in a cylinder 40 on a leg member 39 constituted by a leg stand 37 and leg rods 38, the upper piston 41 is fixed to the upper end of a shaft rod 43 and the lower piston 42 is fixed to the upper end of a pipe shaft 44 loosely fitted on the shaft rod 43. On the lower portion of the pipe shaft 44 is provided a wing piece 45 which is fixed to a lower pressing piece 47 via connecting bars 46. On the other hand, an upper pressing piece 48 is fixed to the lower end of the shaft rod 43. Also, the center portion of a valve tube body 51 supported by two lateral rods 50 spanning between flanges 49 fitted on both ends of the flow passage and the leg members 39 is pressed by the upper and lower pressing pieces 48, 47, then the upper and lower pressing pieces 48, 47 connected to the pistons 41, 42 are symmetrically moved up and down by suitably forcing compressed air into holes 52, 53, 54 in the cylinder 40, so that the valve tube body 51 is opened and closed.
Now, at the present, in an apparatus for manufacturing semiconductors in which various pipeline and control devices are arranged and complicated pipeline design is performed, allowing the apparatus per se to be compact has been required. As a result, a pinch valve used in the pipeline of the apparatus must be compact in order to save space, thus making the pinch valve used in the apparatus compact an important matter. Also, a pinch valve able to regulate a very small flow rate is required.
However, in the pinch valve described as above, since the actuator and the valve body are constituted as separate components, and the leg member 39, the leg stand 37 and the wing piece 45 are provided between the cylinder 40 and the valve tube body 51 which is a flow passage, the overall height of the valve is very large and thus the valve cannot be made compact. Consequently, the above pinch valve cannot be used as a pinch valve in the pipeline of a semiconductor manufacturing apparatus. Also, since, in the pinch valve of such construction, it is difficult to optionally adjust the degree of opening the valve tube body, adjustment of a very small flow rate cannot be performed.
The present invention has been conceived in view of the problems of the prior art as stated above, and the purpose of this invention is to provide a pinch valve the overall height of which is low in comparison with the conventional pinch valve, which is compact, which remarkably improves the durability of the tube body pipelined in the apparatus during opening and closing of the valve, and which is able to adjust a very small flow rate.
In order to achieve the above purpose, as a result of extensive research, the inventors have found that a pinch valve could be made very compact by integrally constituting a drive and a valve body. That is, explaining the constitution of this invention with reference to FIGS. 1 to 8, a pinch valve according to a first embodiment of the invention is characterized in that it comprises a tube body 1 made of an elastic body, a cylinder body 4 having a cylinder portion 2 thereinside and joined to a disk-like cylinder cover 3 at the upper portion thereof, a piston 11 sliding up and down on the inner periphery of the cylinder portion 2 in a sealing manner and having a connecting portion 13 suspending from the center of the lower surface of the piston to penetrate a through hole 5 provided in the center of the lower surface of the cylinder body 4 in a sealing manner, a pressing piece 15 fixed to the lower end of the connecting portion 13 of the piston 11 and contained in an oval slit 6 provided on the bottom surface of the cylinder body 4 perpendicularly to the axis of a flow passage, a body 16 joined and fixed to the lower end surface of the cylinder body 4, having a groove 17 for receiving the tube body 1 on the axis of the flow passage and having grooves 18 for receiving connecting body carriers 20 which are arranged on both ends of the groove 17 and deeper than the groove 17, a pair of connecting body carriers 20 each having a fitting portion 21 fitted in the groove 18 of the body 16 at one end of the carrier 20 and a connecting body carrier port 23 on the inner surface of the other end of the carrier 20 and having a through-hole 26 for receiving the tube body 1, and a pair of air ports 9, 10 provided on the peripheral side surface of the cylinder body 4 and communicating with a first space portion 7 surrounded by the bottom surface and inner periphery of the cylinder portion 2 and the lower end surface of the piston 11, and a second space portion 8 surrounded by the lower end surface of the cylinder cover 3, the inner periphery of the cylinder portion 2 and the upper surface of the piston 11.
The pinch valve according to the first invention is also characterized in that the connecting body carrier 20 is provided at a fitting portion 21 thereof with a ledge portion 22 for preventing the connecting body carrier 20 from slipping out, and the body 16 is provided at the groove 18 thereof with a recessed groove 19 for receiving the ledge portion 22 for preventing the carrier 20 from slipping out.
In addition, the pinch valve according to the first invention is characterized in that a spring 35 is installed in the second space portion 8 in the condition where the spring 35 contacts the cylinder cover 3 and the piston 11, and is also characterized in that a spring 35 is installed in the first space portion 7 in the condition where the spring 35 contacts the bottom surface of the cylinder portion 2 and the piston 11.
Further, the pinch valve according to the first invention is characterized in that a connecting body 29 having an inserting portion 31 formed with an outer diameter larger than the inner diameter of the tube body 1 at one end of the connecting body 29 and inserted in and connected to the tube body 1, a pipeline connecting portion 32 at the other end of the connecting body 29 and a flange portion 33 at the center of the connecting body 29 is fitted in and fixed to the connecting body carrier 20 by engaging a cap nut 34 with the flange portion 33 and screwing the cap nut 34 to a male screw portion 24 provided on the outer periphery of the connecting body carrier 20.
Also, the pinch valve is characterized in that the material of the tube body 1 is EPDM, fluororubber, silicone rubber or a composition of these materials, and is further characterized in that the tube body is made of a composition of polytetrafluoroethylene and silicone rubber.
Although the tube body 1 of the pinch valve according to the invention may be made of EPDM, fluororubber, silicone rubber or an elastic body such as a composition of fluororubber and silicone rubber and is not limited to these materials, a composition of fluororubber and silicone rubber is especially preferable.
Also, although the cylinder body 4 and the body 16 may be made of a material having rigidity, such as metal or plastic, and thus the materials of those components are not especially limited, a fluororesin plastic, such as PVC, PVDF or the like is especially preferable.
Furthermore, explaining the constitution of a pinch valve according to the second invention with reference to FIGS. 15 to 26, the pinch valve is characterized in that it comprises a cylinder body 101 having a cylinder portion 115 provided at the upper portion of the inner surface thereof with a screw portion 114 for adjusting the opening degree and an air port 116 communicating with the lower end portion of the cylinder portion 115, a cylindrical handle 103 having a recess 117 receiving a spring 106 at the lower portion thereof and having a screw portion 118 screwed with the screw portion 114 for adjusting the opening degree at the outer periphery of the lower portion of the handle 103, a disk-shaped spring carrier 105 clamping the spring 106 with the upper end surface of the handle recess portion 117, a connecting bar 104 clamping the spring 106 between the handle 103 and the spring carrier 105 by engaging the connecting bar 14 with the upper portion of the handle 103 and by joining the lower end surface of the connecting bar 104 to the spring carrier 105, a lock nut 110 screwed to a screw portion 118 of the handle 103 to fix the position of the handle 103, a piston 107 sliding up and down on the inner periphery of the cylinder portion 115 in a sealing manner and having a connecting portion 120 suspending from the center of the piston 107 to penetrate a through-hole 119 provided on the center of the lower surface of the cylinder body 101 in a sealing manner, a pressing piece 108 fixed to the lower end portion of the connecting portion 120 and contained in an oval slit 121 provided on the lower end portion of the cylinder body 101 perpendicularly to the axis of the flow passage, a body 102 joined and fixed to the lower end surface of the cylinder body 101 and having a groove 129 which receives a tube body 109 of an elastic body on the axis of the flow passage, and connecting portions connecting the tube body 109 to the other tubes at both sides of the body.
Also, the second invention is characterized in that the handle 103, the spring carrier 105, the connecting bar 104 and the spring 106 are integrally assembled by a bolt 122 penetrating the inside of the spring carrier 105 and the connecting bar 104, and a nut 123.
In addition, the second invention is characterized in that a connecting body 113 having at one end thereof an inserting portion 124 the outer diameter of which is larger than the inner diameter of the tube body 109 and which is inserted in and connected to the tube body 109, a pipeline connecting portion 125 at the other end of the connecting body 113 and a flange portion 126 on the center of the connecting body 113, is fitted in and fixed to a connecting body carrier 111 to constitute the connecting portion by engaging cap nut 112 with the flange portion 126 and screwing the cap nut 112 to a male screw 128 provided on the outer-periphery of the connecting body carrier 111.
Further, the second invention is characterized in that the material of the tube body 109 is EPDM, fluororubber, silicone rubber, or a composition of these materials, and is also characterized in that the tube body 109 is made of a composition of PTFE and silicone rubber.
Although the tube body 109 of the pinch valve according to the second invention may be made of EPDM, fluororubber, silicone rubber or a composition of fluororubber and silicone rubber and is not especially limited to these materials, a composition of fluororubber (for example, PTFE, etc.) and silicone rubber is especially preferable.
Moreover, although the cylinder body 101, the body 102 and the handle 103 may be made of a material having rigidity, such as metal or plastic and thus the materials of those components are not especially limited, a plastic of fluororesin resin, such as PVC, PVDF or the like is especially preferable.
Lastly, although the connecting body 113 constituting the connecting portion may be made of a material having chemical resistance, such as plastic or the like and thus the material of the connecting body is not especially limited, a fluororesin resin, such as PTFE, PVDF, PFA or the like is especially preferable.